Most likely the timing chain guides. Either a guide broke and caused the chain to skip or break, or the chain broke and took out the guide. Either way that's an interference engine so the prognosis is not good. You'd have get inside the engine to see what's really going on. First I'd pull the valve cover and take a look at the chain, and maybe use a bore scope to check condition of the guides.

Plastic bits in oil could be a sign that the cam chain tensioners have distintegrated, which could cause the cam to get out of sync, which would prevent it starting. Fortunately, manufacturers don't put much plastic inside engines - I don't know recent Saabs well, but I cant think of any other source of plastic.